Sand, rarer than one thinks

Sand and gravel are mined world-wide and account for the largest volume of solid material extracted globally. Formed by erosive processes over thousands of
years (John, 2009), they are now being extracted at a rate far greater than their renewal. Furthermore, the volume being extracted is having a major
impact on rivers, deltas and coastal and marine ecosystems (Figure 1), results in loss of land through river or coastal erosion, lowering of
the water table and decreases in the amount of sediment supply. Despite the colossal quantities of sand and gravel being used, our increasing
dependence on them and the significant impact that their extraction has on the environment, this issue has been mostly ignored by policy
makers and remains largely unknown by the general public.

Why is this issue important?

Globally, between 47 and 59 billion tonnes of material is mined every year (Steinberger et al., 2010), of which sand and gravel, hereafter
known as aggregates, account for both the largest share (from 68% to 85%) and the fastest extraction increase (Krausmann et
al., 2009). Surprisingly, although more sand and gravel are mined than any other material, reliable data on their extraction in certain developed countries are
available only for recent years (Krausmann et al., 2009). The absence of global data on aggregates mining makes environmental assessment very difficult and has
contributed to the lack of awareness about this issue.

One way to estimate the global use of aggregates indirectly is through the production of cement for concrete
(concrete is made with cement, water, sand and gravel). The production of cement is reported by 150
countries and reached 3.7 billion tonnes in 2012 (USGS, 2013a). For each tonne of cement, the building
industry needs about six to seven times more tonnes of sand and gravel (USGS, 2013b). Thus, the world’s use
of aggregates for concrete can be estimated at 25.9 billion to 29.6 billion tonnes a year for 2012 alone. This
represents enough concrete to build a wall 27 metres high by 27 metres wide around the equator.

Added to this are all the aggregates used in land reclamation, shoreline developments and road embankments (for which the global statistics are
unavailable), plus the 180 million tonnes of sand used in industry (USGS, 2012). Aggregates also contribute to 90% of asphalt pavements
and 80% of concrete roads (Robinson and Brown, 2002). China alone built 146,400 kilometres of road in one year (EDE, 2013) — an indication of the world demand for aggregates.

Figure 1: Beach sand mining in Sierra Leone.

Taking all these estimates into account, a conservative estimate for the world consumption of aggregates exceeds 40 billion tonnes a year. This is twice
the yearly amount of sediment carried by all of the rivers of the world (Milliman and Syvitski, 1992), making humankind the largest of the planet’s transforming
agent with respect to aggregates (Radford, 2005).

This large quantity of material cannot be extracted (Figure 1) and used without a significant impact on the environment (Sonak et al., 2006, Kondolf, 1994).
Extraction has an impact on biodiversity, water turbidity, water table levels and landscape (Table 1) and on climate through carbon dioxide emissions from
transportation. There are also socio-economic, cultural and even political consequences. In some extreme cases, the mining of marine aggregates has changed
international boundaries, such as through the disappearance of sand islands in Indonesia (New York Times, 2010; Guerin, 2003).

Table 1:Summary of the main consequences of extraction of aggregates.

What are the findings?

The demand for aggregates stems from a wide range of sectors, including production of glass, electronics and aeronautics. However, its largest use is in
construction (see example on Dubai in Box 1) and land reclamation (see example on Singapore in Box 2). The trend for aggregates extraction can be estimated using
cement production as a proxy. This has multiplied three-fold in the last 20 years from 1.37 billion tonnes of cement in 1994 to 3.7 billion tonnes in 2012 (USGS, 2013a)
mainly as a result of rapid economic growth in Asia (UNEP and CSIRO, 2011), and spurred by China’s development, which in 2012 absorbed 58% of the world cement production,
or 2.15 billion tonnes (Figure 2). Five countries — China (58%), India (6.75%), the United States (2%), Brazil and Turkey — produce 70% of the world’s cement (USGS, 2013c).
However, cement demand by China has increased exponentially by 437.5% in 20 years, while use in the rest of the world increased by 59.8% (Figure 2). Each Chinese citizen
is currently using 6.6 times more cement than a U.S. citizen (USGS, 2013a). Demand continues to increase with new infrastructure and renewal of existing infrastructure
(roads, bridges, dams, houses) — all dependent on the availability of aggregates.

Sand was until recently extracted in land quarries and riverbeds; however, a shift to marine and coastal aggregates mining has occurred due to the
decline of inland resources. River and marine aggregates remain the main sources for building and land reclamation. For concrete, in-stream gravel
requires less processing and produces high-quality material (Kondolf, 1997), while marine aggregate needs to be thoroughly washed to remove salt.
If the sodium is not removed from marine aggregate, a structure built with it might collapse after few decades due to corrosion of its metal
structures (Delestrac, 2013). Most sand from deserts cannot be used for concrete and land reclaiming, as the wind erosion process forms round
grains that do not bind well (Zhang et al., 2006).

Figure 2: Left: Cement production from 1994 to 2012 in billion metric tonnes.
Sources: Emissions of CO2 - from Cement Production (CDIAC) as in UNEP Environment Data Explorer (EDE, 2014). Right: Emissions of carbon dioxide from cement production in China.

In developing countries, mining and dredging regulations are often established without scientific understanding of the consequences, and projects
are carried out without environmental impact assessments (Maya et al., 2012; Saviour, 2012). As a result, aggregate mining has affected the
provision, protection and regulation of ecosystem services.

Impact on marine biodiversity

The mining of marine aggregates is increasing significantly. Although the consequences of substrate mining are hidden, they are tremendous (Figure 3).
Marine sand mining has had an impact on seabed flora and fauna (Krause et al., 2010). Dredging and extraction of aggregates from the benthic (sea bottom) zone
destroys organisms, habitats and ecosystems and deeply affects the composition of biodiversity, usually leading to a net decline in faunal biomass and
abundance (Desprez et al., 2010) or a shift in species composition. Long-term recovery can occur only where original sediment composition is being restored (Boyd et al., 2005).

Aggregate particles that are too fine to be used are rejected by dredging boats, releasing vast dust plumes and changing water turbidity, resulting in
major changes to aquatic and riparian (i.e. river banks) habitats over large areas (Ashraf et al., 2011).

The mining of aggregates in rivers (Figure 4) has led to severe damage to river basins (Sreebha and Padmalal, 2011), including pollution and changes in
levels of pH (Saviour, 2012). Removing sediment from rivers causes the river to cut its channel through the bed of the valley floor (or channel incision)
both upstream and downstream of the extraction site. This leads to coarsening of bed material and lateral channel instability. It can change the riverbed
itself (Kondolf, 1997). The removal of more than 12 million tonnes of sand a year from the Vembanad Lake catchment in India has led to the lowering of the
riverbed by 7 to 15 centimetres a year (Padmalal et al., 2008). Incision can also cause the alluvial aquifer to drain to a lower level, resulting in a
loss of aquifer storage (Kondolf, 1997). It can also increase flood frequency and intensity by reducing flood regulation capacity. However, lowering the
water table is most threatening to water supply (Myers et al., 2000) exacerbating drought occurrence and severity as tributaries of major rivers dry
up when sand mining reaches certain thresholds (John, 2009).

Coastal and inland erosion

Figure 5:Completed in 1990 at a cost of US$ 70 million,
a tetrapod wall was constructed to prevent coastal erosion along the edges of the Male in the Maldives.

Erosion occurs largely from direct sand removal from beaches, mostly through illegal sand mining. It can also occur indirectly, as a result of
near-shore marine dredging of aggregates, or as a result of sand mining in rivers (Kondolf, 1997). Damming and mining have reduced sediment delivery
from rivers to many coastal areas, leading to accelerated beach erosion (Kondolf, 1997). Onshore sand mining in coastal dune systems such as those in
Monterey Bay, California, in the United States, can also lead to long-term erosion, in this instance, 0.5 to 1.5 metres a year (Thornton et al., 2006).

By 2100, global average sea level rise is expected to reach 0.26 to 0.55 metres under the best-case scenario (of 70% reduction of greenhouse gas emissions),
and nearly one metre under unabated increase in greenhouse gas emissions (IPCC, 2013a). This problem is particularly acute for small islands states, where
retreat options are limited. In the Maldives, a few of the largest and highest islands, such as the capital city, Male, are being consolidated to ensure
they can host the population displaced from low-lying islands (Figure 5). To strengthen the city, a large amount of sand is being imported to Male, to be
used in building higher towers and coastal protection. The sand is taken from offshore sand islands. Paradoxically, the sands extracted for the protection
measures in Male are leading to the lowering of some islands, increasing the need to relocate their populations (Delestrac, 2013).

Lake Poyang, the largest freshwater lake in China, is a distinctive site for biodiversity of international importance, including a Ramsar Wetland. It is
also the largest source of sand in China (De Leeuw et al., 2010) and, with a conservative estimate of 236 million cubic metres a year of sand extraction,
may be the largest sand extraction site in the world. By comparison, the three largest sand extraction sites in the United States combined represent 16
million cubic metres a year (De Leeuw et al., 2010). Sand mining has led to deepening and widening of the Lake Poyang channel and an increase in water
discharge into the Yangtze River. This may have influenced the lowering of the lake’s water levels, which reached a historically low level in 2008 (De Leeuw et al., 2010).

Box 1: Dubai

The city of Dubai in the United Arab Emirates is among the world’s most spectacular architectural developments, albeit one that has put significant pressure
on marine aggregates. The Palm Jumeirah, an artificial set of sand islands (see below), required 186.5 million cubic metres (385 million tonnes) of sand and 10 million
cubic metres of rock, and cost US$12 billion (Jan De Nul group, 2013). Its own marine sand resources being exhausted, Dubai imported sand from Australia, for example,
to build the Burj Khalifa tower (Delestrac, 2013), the highest building in the world at 828 metres. While such development is impressive, in 2013, 31% of office
space was vacant in the centre of Dubai (Jones Lang LaSalle, 2013). The Palm Jumeirah was quickly followed by a second Palm project, The Palm Jebel Ali, and then by The
World islands project, a set of 300 artificial islands representing a map of the world. The World project cost US$14 billion to construct and required 450 million
tonnes of sand. Only a very small number of these islands currently host infrastructures. These land reclamation projects exhausted all of the marine sand resources
in Dubai (Delestrac, 2013).

Left: Dubai February 2002 ASTER image. Right: July 2012 ASTER image. The two Palm islands and The World
artificial islands required more than 750 million tonnes of sand. Images processed and analysed by UNEP/GRID-Geneva.Full Size Image

Impact on climate

The transport of large quantity of aggregates, sometimes over long distances, has a direct impact on greenhouse gas emissions. The indirect
impacts of aggregate mining come from the production of cement. For each tonne of cement, an average of 0.9 tonnes of carbon dioxide are
produced (Mahasenan et al., 2003; USGS, 2012) . The Carbon Dioxide Information Analysis Center (CDIAC) estimates that 1.65 billion tonnes of
carbon dioxide emissions were from cement production in 2010 alone, or nearly 5% of total greenhouse gas emissions (EDE, 2014). Total carbon
emissions from cement amount to eight billion tonnes of carbon (equivalent of 29.3 billion tonnes of carbon dioxide) (IPCC, 2013b, p. 474)
and has increased from 3% in the 1990s to 4% of greenhouse gas emissions from 2000 to 2009 (IPCC, 2013b, p.489).

Economic impact

Aggregates are, in most cases, a free resource, but their extraction comes at the expenses of other economic sectors and local livelihoods.
Tourism may be affected through beach erosion (Kondolf, 1997), while fishing — both traditional and commercial — can be affected through
destruction of benthic fauna (Cooper, 2013; Desprez et al., 2010). Agriculture could be affected through loss of agricultural land from
river erosion (John, 2009) and the lowering of the water table (Kondolf, 1997). The insurance sector is affected through exacerbation of the
impact of extreme events such as floods (Kondolf, 1997), droughts (John, 2009) and storm surges through decreased protection of beach fronts
(Thornton et al., 2006). The erosion of coastal areas and beaches affects houses and infrastructure (Thornton et al., 2006; John, 2009). A
decrease in bed load or channel shortening can cause downstream erosion including bank erosion and the undercutting or undermining of
engineering structures such as bridges, side protection walls and structures for water supply (John, 2009; Padmalal et al., 2008).

A lack of proper scientific methodology for river sand mining has led to indiscriminate sand mining (John, 2009), while weak governance and
corruption have led to widespread illegal mining (Saviour, 2012; Ashraf et al., 2011). Sand trading is a lucrative business, and there is evidence
of illegal trading such as the case of the influential mafias in India (Ghosh, 2012).

In Morocco, half of the sand – 10 million cubic metres a year – comes from illegal coastal sand mining (Au fait, 2011). Sand smugglers have
transformed a large beach into a rocky landscape between Safi and Essouira (l’Economiste, 2005; Khardijamal, 2011). Sand is often
removed from beaches to build hotels, roads and other tourism-related infrastructure. In some locations, continued construction is likely to
lead to an unsustainable situation and destruction of the main natural attraction for visitors — beaches themselves.

What are the implications for policy?

The lack of adequate information is limiting regulation of extraction in many developing countries (Sreebha and Padmalal, 2011). Access to data
is difficult, and data are not standardised. There is limited collaboration/co-ordination between the marine scientific research establishments
and the marine aggregates industry (Velegrakis et al., 2010). Except in the European Union, regulation efforts are few, especially in
developing countries (Sreebha and Padmalal, 2011). Lack of monitoring systems, regulatory policies and environmental impact assessments
have led to indiscriminate mining, triggering severe damage to the environment and related ecosystem services.

Box 2: Singapore

A map of Singapore shows its area increasing from 1973 to 2013.
Remote sensing analysis: UNEP/GRID-Geneva.Full Size Image

Singapore is developing rapidly and its population has increased by a factor of three since 1960, from 1.63 million to 4.84 million
inhabitants in 2010. Given its small area, Singapore needed more space for its infrastructure development. To respond to this demand, the city has
increased its land area by more than 20 in the last 40 years (an addition of 130 square kilometres), mostly by using aggregates to reclaim
land from the sea (see map).

Having imported a reported 517 million tonnes of sand in the last 20 years, Singapore is by far the largest importer of sand world-wide
(UN Comtrade, 2014; Aquaknow, 2014) and the world’s highest per capita consumer of sand at 5.4 tonnes per inhabitant.

Sand is typically imported mostly from Indonesia, but also from the other neighbouring countries of Malaysia, Thailand and Cambodia. Export of
sand to Singapore was reported to be responsible for the disappearance of some 24 Indonesian sand islands. It is reported that this triggered
political tensions regarding maritime borders between the two countries (New York Times, 2010; Guerin, 2003).

The reported sand exported from Indonesia to Singapore declined sharply since a temporary ban declared in February 2002 (Guerin, 2003). Other
neighbouring countries are now reporting few exports to Singapore. Overall, the reported total amount of sand imported by Singapore
(517 million tonnes) and the sum of sand exports to Singapore from its four neighbouring countries (637 million tonnes) does not match
(see graph left), showing an underestimation of 120 million tonnes of sand imports. Obviously, these statistics do not include illegal
imports and highlight the need for better monitoring. There is also an alleged illegal sand trade (Global Witness, 2010). As the price of
sand increases, so does the traffic of sand by local mafias (Global Witness, 2010; Milton 2010; Handron, 2010). The average price of sand
imported by Singapore was US$3 per tonne from 1995 to 2001, but the price increased to US$190 per tonne from 2003 to 2005 (UN Comtrade, 2014).

Reducing consumption of sand

One way to reduce consumption of sand is to optimise the use of existing buildings and infrastructure. Recycled building and quarry dust
material can be a substitute for sand. Despite the very high value of minerals found in the sand, it is mostly used for concrete or is
buried under highways. Concrete rubble should be recycled to avoid using aggregates, at least for low-quality uses (Kondolf, 1997).
Recycling glass bottles would also reduce sand consumption.

Substitutes for sand are available. Khamput (2006) showed that quarry dust could be used to replace sand in general concrete structures.
The replacement of sand by up to 40% of incinerator ash exhibits higher compressive strength than regular cement mortars (Al-Rawas et al.,
2005). Some desert sand can be used if mixed with other material (Cisse et al., 2012; Zhang et al., 2006). There are alternatives for building
houses, including wood, straw and recycled material. However, the current building industry is geared toward concrete know-how and equipment.
Training of architects and engineers, new laws and regulations, and positive incentives are needed to initiate a shift for lowering our
dependency on sand. Renewable and recycled materials need to be targeted for building houses and roads.

Tax on aggregates extraction to create incentives on alternatives

The current situation will continue unless sand extraction is correctly priced and taxed so that other options become economically viable.
Despite the increasing rarity of sand, in the United States the price of sand has remained very stable, fluctuating from US$4.50 to US$6.7
a tonne between 1910 and 2013 (USGS, 2012) . Because sand is still very cheap – sand itself is freely accessible; only extraction costs
need to be covered – there is little or no incentive to induce a change in our consumption.

Alternative sources of sand and gravel, which accumulate at the bottom of dams, can also be targeted. Their use would address the
problem of these aggregates accumulating which leads to a reduced capacity of dams to store water and could result in the dams’ water
intakes being blocked. Dams regularly release large amounts of water to flush out aggregates. Although currently more expensive,
aggregates could be extracted from the dams.

Reducing the negative consequences of extraction

The environmental impact of in-stream mining might be avoided if the annual bed load were calculated and the mining of aggregates restricted
to that value or less (Ashraf et al., 2011). Local environments should be studied to define the limits of acceptable changes (Cooper et al., 2011; Cooper, 2013).

Policies

Whilst it is critical for political leaders to take appropriate measures, the mining of aggregates has not yet reached their political agenda.
This is primarily because sand loss has not yet reached a level of scarcity that would threaten the economy. Few, if any, measures are being
implemented (See Box 3), with the notable exception of the European Union, and the United Kingdom in particular (Velegrakis et al., 2010;
Tillin et al., 2011). There is a need for regulating sand extraction in both national and international waters. Experts recommend that
large-scale mining, quarrying and reclamation activities should be authorized only after sound scientific assessment shows there would be
limited impact on the environment (Maya et al., 2012). Other policy actions include the introduction of scientific mining operations, followed
by ecological restoration. Greater consideration of substitute and sustainable use of the resource could drastically reduce impact on the environment (Chauhan, 2010).

Box 3. Relevant existing policies

Activity-based regulations and land and marine protection are the two policy frameworks that govern extraction of aggregates. Land and marine
protected areas do include restrictions on extraction of aggregates within their limits. However, extractions near these protected areas can indirectly
affect these sites, such as in the case of sand extraction near Poyang Lake in China (a Ramsar site), which affected the lake water level and turbidity.

No international conventions regulate the extraction, use and trade of land-based sand (sand quarry, riverine and lake aggregate). Due to operational
costs, most marine aggregate extractions are carried out at short distances from landing ports and at water depths of less than about 50 metres. As
these activities occur close to shore, they generally are under national jurisdictions. The same applies to Exclusive Economic Zones or to the
Continental Shelf, where coastal states exercise sovereign rights to explore and exploit natural resources (Radzevicius et al., 2010). Hence the
need to have appropriate national policies.

Several important international conventions exist. The United Nation Convention on the Law of the Sea, 1982 (UNCLOS) provides for the delimitation
of maritime zones and regulates rights and obligations in respect of usage, development and preservation for these zones, including resource mining (Radzevicius et al., 2010).

A number of regional conventions have been ratified with the aim of minimizing the impact of human activities and that include, directly or indirectly,
references to aggregate exploitation. These include the Convention for the Protection of the Marine Environment of the North East Atlantic, 1992 (OSPAR
Convention), the Convention on the Protection of the Marine Environment of the Baltic Sea Area, 1992 (Helsinki Convention), the Convention for the
Protection of the Mediterranean Sea against Pollution, 1976, and Convention for the Protection of the Marine Environment and the Coastal Region of the
Mediterranean, 1995 (Barcelona Convention). However, there are no specific guidelines for the management of marine aggregates extraction under the Barcelona
Convention. Others include the Convention for the International Council for the Exploration of the Sea (ICES), 1964, the Convention on Environmental Impact
Assessment in a transboundary context, 1991 (ESPOO Convention), the Protocol on Strategic Environmental Assessment, 2003 (SEA Protocol), and the Protocol on
land-based sources of pollution from the Convention for the Protection and Development of the Marine Environment in the Wider Caribbean Region (Cartagena Convention).

The governance is not coherent and includes several layers of regulations between national and international conventions. There are no global standards (Velegrakis et al.,
2010; Radzevicius et al, 2010).

Conclusion

Sand and gravel represent the highest volume of raw material used on earth after water. Their use greatly exceeds natural renewal rates.
Moreover, the amount being mined is increasing exponentially, mainly as a result of rapid economic growth in Asia (UNEP and CSIRO, 2011).
Negative effects on the environment are unequivocal and are occurring around the world. The problem is now so serious that the existence of river
ecosystems is threatened in a number of locations (Kondolf, 1997; Sreebha and Padmalal, 2011). Damage is more severe in small river catchments.
The same applies to threats to benthic ecosystems from marine extraction (Krause et al., 2010; Desprez et al., 2010; Boyd et al., 2005).

A large discrepancy exists between the magnitude of the problem and public awareness of it. The absence of global monitoring of aggregates
extraction undoubtedly contributes to the gap in knowledge, which translates into a lack of action. As this issue is truly a major emerging one,
there is a need for in-depth research. The implementation of a monitoring mechanism regarding global aggregate extractions and trade would shed
light on the magnitude of this issue and bridge the current data and knowledge gap (Velegrakis et al., 2010). This would also raise this issue
on the political agenda and perhaps lead to an international framework to improve extraction governance, as the current level of political concern
clearly does not match the urgency of the situation.

Cisse, A., Tamba, S., Lo, M.L., Diop, M.B., Sissoko, G., 2012. Contribution to Improving the Performance of Concrete: The Case of the Use of Desert Sand of the Region of Dakar. Research Journal of Environmental and Earth Sciences 4(12), 1071-1078.

Khamput, P., 2006. A study of compressive strength of concrete using quarry dust as fine aggregate and mixing with admixture Type E. Department of Civil Engineering, Rajamangala University of Technology, Thailand.

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